Field of the Invention
The present invention relates to an encrypted file printing system, an encrypted file printing method, and an encrypted file print control program, and more particularly, relates to an encrypted file printing system that performs printing after decrypting and rasterizing an encrypted file, an encrypted file printing method, and an encrypted file print control program.
Description of the Related Art
Example printing methods to be implemented in image forming apparatuses such as multi-functional peripherals (MFP) and printers include a printing method by which a special-purpose printer driver is installed into a client PC, and printing is performed with an application such as Office (a registered trade name) of Microsoft or Adobe Reader (a registered trade name) of Adobe Systems, and a printing method by which a file in a format compatible with direct printing, such as OOXML (Office Open XML), ODF (OpenDocument Format), or PDF (Portable Document Format) (in the description below, PDF is used), is transmitted directly to MFP or a printer without the use of any application, and then, printing is performed.
As the demand for security has been increasing recently, files such as PDF files are not protected only with passwords, but are protected by a technology called Rights Management System (RMS). RMS is to encrypt a file by adding authorization information called policy about each user to the file, inquire of an authorization management server about the authorization information through an application in a client PC when a user accesses the file from the client PC, cancel the encryption and allow viewing if viewing is authorized, and set, for each user, restrictions on functions such as editing and printing according to the policy. In a case where any printing authority has not been given to a user who is viewing, the print button is shown in gray to prohibit printing from an application. In a case where the printing authority has been given to the user, the print button is shown in a normal state to allow printing from an application.
In a case where a file protected with a technology such as the above-described RMS is to be transmitted directly to MFP or a printer and be subjected to direct printing, the file not only needs to be processed according to the policy, but also needs to be decrypted before rasterized and converted into image data.
As for printing that uses an encrypted file but is not related to direct printing of an encrypted file, for example, JP 2008-93903 A discloses an image information processing system that includes: a portable removable large-capacity storage device that characteristically includes a disk controller unit that controls at least a large-capacity storage device, an encrypting/decrypting unit, a user authenticating unit, and a nonvolatile memory unit; and an image information processing device on which the removable large-capacity storage device can be mounted.
JP 2006-185053 A discloses an image processing device that includes: an input unit that inputs print data; a generating unit that generates image data from the print data; a storing unit that stores the image data into a storage; a notifying unit that issues a notification about the generation state of the image data in the generating unit; and an output unit that outputs the stored image data in accordance with authentication information that has been input.
JP 2011-213098 A discloses a printing system that includes: a drawing/deploying unit that receives print data from a host, converts the print data into raster data, and allots a unique job ID to the raster data to turn the raster data into encoded data; a print control unit that obtains, from the drawing/deploying unit, encoding information indicating the load for performing encoding when the drawing/deploying unit generates the encoded data, determines the level of the speed in printing the raster data having the job ID allotted thereto, and reorders the sequence of the job IDs in a job sequence table that specifies the job print sequence in accordance with the levels of printing speeds; and a print engine unit that prints the raster data with the reordered job ID at the printing speed associated with the job ID.
When an encrypted file is decrypted (particularly, when complicated encryption incorporated into RMS is deciphered), a large load is put on the central processing unit (CPU). Therefore, in a case where the same control as that of the above-described application is simply performed by an image forming apparatus, printing performance degrades when decryption and rasterization are performed in parallel. Particularly, in the case of production printing where direct printing of a large-sized file or a file with a complicated structure is performed, the degradation of printing performance becomes a serious problem in terms of productivity.
Furthermore, since the file structure (such as the file size, the number of pages, and the file/object type) of an encrypted file is not clear unless the encrypted file is decrypted, the times to be required for a decryption process and a rasterization process cannot be calculated, and therefore, it is difficult to predict a required print time.